It is well known for electrical appliances, such as hair dryers, to draw electrical power through connection to a power source, such as an electrical outlet. Specifically, the electrical appliance (which serves as the load of the electrical system) is connected to the power source by a pair of current-carrying wires. The pair of current-carrying wires typically include a hot wire and a neutral wire, the pair of wires having equal but opposite magnitudes under normal conditions.
On occasion, the electrical system may experience a ground fault condition while the load is connected to the power supply. A ground fault condition occurs when the differential between the values of the currents of the two wires exceeds a predetermined value. Often a ground fault will occur if the hot line becomes inadvertently grounded. A ground fault condition can result in a loss of power to the electrical appliance because current is unable to flow to the load. As a consequence, an excessive amount of current tends to flow into the ground conductor of the electrical system which, in turn, creates dangerous voltage levels at points in the circuit that should be at ground potential. This condition can result in potentially dangerous electrical shocks, which could seriously injure an individual.
Accordingly, ground fault safety devices are commonly employed in such electrical systems to eliminate ground fault conditions. One type of ground fault safety device is the ground fault circuit interrupter (GFCI). Another type of ground fault safety device is the appliance leakage current interrupter (ALCI). Ground fault circuit interrupters are used to eliminate ground fault conditions as well as grounded neutral conditions, whereas appliance leakage current interrupter are used only to eliminate ground fault conditions.
Both types of ground fault safety devices prevent ground fault conditions from occurring by opening the electric circuit upon the detection of a ground fault condition in the pair of wires. It is known to incorporate GFCI's and ALCI's into electrical plugs, electrical switches and electrical receptacles.
GFCIs and ALCIs are commonly mounted within a generally rectangular housing having a top, a bottom, a front end and a rear end. The housing is attached to the appliance by an electrical cord which extends into the housing from the rear end. A pair of prongs (blades) typically extend out from the housing and are sized, shaped and spaced away from each other so that they can be inserted into the sockets of an electrical outlet, thus making contact and closing the circuit.
The electrical cord is connected inside the housing to a terminal block. Access to the terminal block often requires that the housing be disassembled to reveal the terminal block connections. However, disassembly of the housing usually exposes the GFCI or ALCI circuitry to potential damage which may not be discovered until operation, leading to potentially catastrophic damage and/or injury.
Furthermore, components used to build the GFCI and ALCI circuits include discrete components (e.g., diodes, resistors, capacitors, etc), printed circuit boards (PCBs), solenoids, and relays. The relative location of these components, including electrical PCB traces, is critical to prevent electrical arcing between the components. Thus, there must be sufficient housing volume to allow for sufficient spacing between components and electrical PCB traces to prevent the risk of arcing between the components. However, the housing enclosing the circuits and the terminal block is constrained in certain dimensions according to electrical codes and standards.
Furthermore, the GFCI and/or ALCI circuits are susceptible to moisture damage. Consequently, there exists a need to prevent or retard moisture seepage into the circuit area. Where the terminal block and the circuitry share a common space, as in the prior art, moisture seepage into the common space may cause unknown circuitry damage to the GFCI tripping circuit and/or hardware leading to potentially catastrophic damage and/or injury.
Similarly, circuit breakers with ground fault or arc fault systems typically include a self-test button. These button designs usually include a mechanical spring, a secondary contact, and a hard-plastic Push to Test (PTT) button. The test button is typically biased by a mechanical force provided by the spring. As the test button is depressed, the mechanical spring makes contact with a secondary contact. The secondary contact can be made of a similar material as the mechanical spring and may have spring type properties, or the secondary contact may be a stationary pin mounted on a printed circuit board (PCB).
One disadvantage is that a gap between the test button and a housing of the circuit breaker is present before or during when the button is depressed. When the gap between the button and the housing is present, several concerns arise related to moisture, corrosion, and potential electric shock. With the gap present, internal components are exposed to outside moisture and/or other containments that could disable the tripping functions of the test button. Although PCB's are typically conformal coated, this does not guarantee that moisture could not damage the PCB and/or related electrical components and disable the push to test button and/or present the possibility of the a user being exposed to electrical shock.